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FZJ-2019-02401

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Photothermische Deflexions-Spektroskopie als Charakterisierungsmethode für Dünnschichtsolarzellen auf der Basis von amorphem Silizium

Höhne, N. (Corresponding author)FZJ*

1998
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/22036

Report No.: Juel-3439

Abstract: The potential of photothermal deflection spectroscopy (PDS) as a method to characterise solar cells based on amorphous silicon was studied in this thesis. It was demonstrated, how the proportions of the loss mechanisms of a solar cell under opperating conditions can be obtained from PDS measurements as a function of the wavelength of the incident light. In addition, significant movement of heat sources in the layer system of the solar cell, such as the transition from absorption in the layers to absorption in the glass substrate can be detected using the phase of the PDS signal. However, detection of a change of the heat souree distribution within the deposited layers of the solar cell was restricted by insufficient experimental resolution of the method. In particular, for the comparison with the experimental results, the dynamic heat transport within a layer system was simulated starting from a given heat source distribution and the expected amplitude and phase of the PDS signal was calculated. Experimental conditions were established to reach a high signal stability (1 % in amplitude, 0.1 $^{\circ}$ in phase) in order to resolve small phase shifts. Calibration experiments and theoretical calculations predict a phase shitt of 0.35±O.15°, if the heats source moves $\mu m$ within the i-Iayer of a-Si:H PIN solar cell. However, phase shifts as a result of changes in the applied voltages, which are expected to be even smaller, could not be resolved experimentally. From PDS spectra at different voltages, the proportions of the loss mechanisms as a function of the wavelenght were derived. Values for a standard a-Si PIN solar cell under AM 1.5 illumination were as follows: reflection 28%; absorption without carrier separation 34%; thermalisation of carriers and losses in p- and n-layer 25%; field losses 2%, additional loss through recombination 1 %, leaving an electrical efficiency of 10% at an absolute uncertainty of 10%. The decrease in efficiency of a standard a-Si PiNsolar cell due to degradation was caused by increase in recombination. The quantum efficiency obtained from PDS measurements shows excellent agreement with the values derived by Differential Spectral Response (DSR).

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Contributing Institute(s):

1. Publikationen vor 2000 (PRE-2000)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

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